bjoernager/rust
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Suggest return type

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This commit is contained in:
Esteban Küber 2021-04-08 15:27:43 -07:00
parent 147649d4b9
commit 5af3dec59f
7 changed files with 67 additions and 8 deletions
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28
compiler/rustc_typeck/src/check/compare_method.rs
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@ -329,7 +329,33 @@ fn compare_predicate_entailment<'tcx>(
);
}
TypeError::ArgumentMutability(i) | TypeError::ArgumentSorts(_, i) => {
if let Some(trait_ty) = trait_sig.inputs().get(*i) {
if trait_sig.inputs().len() == *i {
// Suggestion to change output type. We do not suggest in `async` functions
// to avoid complex logic or incorrect output.
let impl_m_hir_id =
tcx.hir().local_def_id_to_hir_id(impl_m.def_id.expect_local());
match tcx.hir().expect_impl_item(impl_m_hir_id).kind {
ImplItemKind::Fn(ref sig, _)
if sig.header.asyncness == hir::IsAsync::NotAsync =>
{
let (span, sugg) = match sig.decl.output {
hir::FnRetTy::DefaultReturn(sp) => {
(sp, format!(" -> {} ", trait_sig.output()))
}
hir::FnRetTy::Return(hir_ty) => {
(hir_ty.span, trait_sig.output().to_string())
}
};
diag.span_suggestion(
span,
"change the output type to match the trait",
sugg,
Applicability::MachineApplicable,
);
}
_ => {}
};
} else if let Some(trait_ty) = trait_sig.inputs().get(*i) {
diag.span_suggestion(
impl_err_span,
"change the parameter type to match the trait",